The more time that individual frogs spend at 25°C, the less likely they were to be infected with amphibian chytrid fungus they report in Scientific Reports .

"This is the first research to show that the history of temperatures that frogs spend their time in affect whether or not they're likely to be infected in nature," says Rowley.

She says the findings have important implications for frog conservation.

The amphibian chytrid fungus Bactrachochytrium dendrobatidis, which attacks the frogs' skin, has decimated amphibian populations around the world, particularly in North Queensland and Central America.

But many species of amphibians that have been decimated by the fungus in one environment, co-exist with it in others.

"It infects most species of amphibians but it doesn't have the same impact on all of them," says Rowley.

Temperature has long been suspected to play a role in infection.

"When you grow the fungus in the lab it does best between 17 and 25°C," says Rowley.

"If you put a frog in a tank and raise the temperature we know that you can actually cure the frog."

Infection rates peak in the colder months and are more likely to affect species at higher elevations she adds.

"So there are patterns that correlate with temperature, but we didn't know if temperature made a difference to individual frogs in the wild."

Radio tracking

To investigate the relationship between infection and body temperature the researchers studied three species of frog infected with amphibian chytrid fungus.

The Stoney Creek frog (Litoria lesueuri ) is known to be infected but hasn't declined; the green-eyed tree frog (Litoria serrata) has declined but made a comeback; and the endangered waterfall frog (Litoria nannotis), which has disappeared from sites above 400 metres.

The frogs were tracked in the summer, wet and winter, dry seasons at four different rainforest sites and their body temperatures were recorded every day and night.

The researchers found that Stoney Creek frogs, which spend their time at higher temperatures were less likely to be infected than the waterfall frog that hide in water all day.

"But frogs of all the species were very likely to be uninfected if 75 per cent of their time was spent above 25 degrees," says Rowley.

The findings challenge a hypothesis known as behavioural fever that suggests infected frogs move to warmer locations to elevate their body temperature and treat the infections.

"In the past, population studies have showed the overall temperature of the frogs increase when the infection goes through, but that wasn't looking at individual frogs over time."

"We can't rule it out, but there's not strong support for behavioural fever because the hotter frogs were the ones that weren't infected."

Rather the new findings seem to suggest that individual frogs that spend time at warmer locations, perhaps to aid in digestion or reproduction, are less prone to infection, says Rowley.

Alternatively, it is also possible that infected frogs don't move as much and so they get cooler and they die.

"We don't know entirely but regardless, the body temperatures explained a lot and it has conservation implications."

Saving frogs

Rowley says the research suggests it may be possible to save endangered species by modifying their habitat to help elevate their body temperature.

"It could be as simple as making a small gap in the canopy," she says.

It may also help scientists find populations of frogs thought to be extinct such as the armoured mist frog (Litoria lorica) that was recently rediscovered living at the edges of the rainforest by Alford and Dr Robert Puschendorf from James Cook University.

"They're the kind of places where there are more gaps in the canopy, and frogs were able to potentially achieve a higher body temperature."